As to the religious test, I should conceive that it can imply
at most nothing more than that without that exception, a
power would have been given to impose an oath involving
a religious test as a qualification for office. The constitution
of necessary offices being given to the Congress, the
proper qualifications seem to be evidently involved. I think
too there are several other satisfactory points of view in
which the exception might be placed.

The Papers of James Madison. Edited by William T. Hutchinson et al. Chicago and London: University of Chicago Press, 1962--77 (vols. 1--10); Charlottesville: University Press of Virginia, 1977--(vols. 11--).